1. Field of the Invention
This invention relates to a process utilizing a substantially hydrogen chloride-free active catalyst system for dimerizing and codimerizing alpha olefins. This invention further relates to the active catalyst system and to the process for preparing this system.
2. Description of Material Information
Olefin dimerization and codimerization processes are known in the art.
Such processes include those which utilize catalysts prepared from tungsten compounds, anilines, and alkyl aluminum halides. Among these processes are those disclosed in U.S. Pat. Nos. 3,784,629, 3,784,630, and 3,784,631. These patents disclose dimerization and codimerization processes employing catalyst systems comprising at least one organometallic compound, at least one amine ligand, and the reaction product of at least one tungsten salt with at least one acidic compound (U.S. Pat. No. 3,784,629); at least one phenolic compound (U.S. Pat. No. 3,784,630), and at least one diketone (U.S. Pat. No. 3,784,631).
U.S. Pat. Nos. 3,813,453, 3,897,512, and 3,903,193 disclose catalyst systems comprising tungsten salts, anilines, and aluminum alkyl halides. Various ranges for the relative proportions of catalyst components are disclosed in these patents. These ranges, given as molar ratios, are listed in Table I.
TABLE I ______________________________________ Molar Ratio U.S. Pat. No. Al W N ______________________________________ 3,784,629 4-40 1 3-1 3,784,630 4-40 1 3-1 3,784,631 4-40 1 3-1 3,813,453 5-200 1 3-1 3,897,512 3-50 1 4-1 3,903,193 5-100 1 0.5-2.5 ______________________________________
There is no indication in any of these references that the processes shown therein are actually operative throughout the entire range of these component proportions. In particular, there is no showing of operability for A1:W ratios at the lower ends of these ranges.
For instance, in each of U.S. Pat. Nos. 3,784,629, 3,784,630, and 3,784,631, the sole example utilizes an A1:W molar ratio of 10:1. The example of U.S. Pat. No. 3,813,453 utilizes an A1:W molar ratio of 2.5:0.031, or approximately 80.6:1, while the U.S. Pat No. 3,903,193 examples show molar ratios of 20:1 and 30:1. Significantly, in U.S. Pat. No. 3,897,512, the lowest A1:W molar ratio shown in the examples is 10:1, although the disclosed ranges provide for a lower limit of 3:1.
Two additional publications pertaining to such catalyst systems are MENAPACE et al., "Changing the Reaction Paths of A Metathesis Catalyst", Journal of Organic Chemistry, Vol. 40, p. 2983 (1975), and MENAPACE et al., "Common Intermediates in Metathesis and Dimerization Reactions" ACS Div. of Petroleum Chemistry, Preprints, Vol. 19, pp. 150-153, No. 1, February (1974).
Both articles show a plot of propylene dimerization activity against A1:W ratio for an ethylaluminum sesquichloride cocatalyst which shows no dimerization activity at A1:W=3:l. The former article, at p. 2984, does show a plot for the conversion of propylene with an ethylaluminum dichloride cocatalyst having an A1:W ratio in the range of 0.5:1 to 3:1. In this range, the article indicates that metathesis and dimerization occur simultaneously.
However, it is further specified therein that this is not propylene dimerization; rather, what is occurring is dimerization of the ethylene resulting from propylene metathesis, and codimerization of the ethylene with propylene. As specifically stated at the end of the paragraph spanning the first and second columns of page 2984, increasing the A1:W ratio results in predomination of dimerization.
As to the proportion of Al to W required to render the catalyst system operative, it is noted that none of these references discloses or suggests the removal of the hydrogen chloride, resulting from formation of the complex from the tungsten salt and the aniline, from the catalyst solution. It is the presence of this hydrogen chloride, either in the catalyst solution or chemically combined, which necessitates the higher molar ratio of aluminum to tungsten.
The catalyst formation process of the present invention provides for the removal, or evolution, from the catalyst solution of the hydrogen chloride resulting from the formation of the complex between the tungsten compound and the aniline. As a result, an active catalyst system for olefin dimerization (with no metathesis) can be formed with a molar ratio of A1:W as low as 2:1.